If you sand the BC, then reshoot another coat on top of that, then clear. I try to clear within a 24 hour period. Also what temp of Basemaker did you use. DuPont has Low temp, mid temp, and Hi temp. Using one of these will vary your dry times of the basecoat. I shot some panels the other day, used a mid temp, as the garage was around 72, then cleared an hour or so later. The panels turned out great. A hi temp basemaker slows your dry times and a Low temp basemaker hastens up your dry times.